# Thread: Topology Proofs, Bases

1. ## Topology Proofs, Bases

1) B={(a,b)|a,b are rational numbers} is a countable base for the usual topology for the real numbers.

2) For any topologies T1 and T2 for X, if B1 is a base for T1 and B1 is a subset of T1, then T1 is a subset of T2

2. ## Re: Topology Proofs, Bases

Where are you stuck? Is it clear that B is countable in the first question?